Hope and help for triple-negative (TNBC) and other forms of hormone-negative breast cancer.

Monday, April 4, 2011

Vitamin D Reduces Risk for ER+, But May Increase ER- Risk

Orlando, Fla. -- In mice models of breast cancer, researchers at the Georgetown Lombardi Comprehensive Cancer Center, a part of Georgetown University Medical Center, found that vitamin D significantly reduced development of estrogen receptor-positive (ER+) breast cancer both in lean and obese mice, but had no beneficial effect in estrogen receptor-negative (ER-) cancer. In fact, obese mice destined to develop ER- breast cancer were clearly worse off than lean ER- mice if they were given vitamin D in their diet.

The researchers, who will present their study at the American Association for Cancer Research (AACR) 102nd Annual Meeting 2011, also found that vitamin D reversed insulin resistance in obese mice, no matter which breast cancer subtype they later developed. In lean mice, however, there was no evidence that vitamin D increased insulin sensitivity.

"Use of vitamin D supplementation is clearly tricky. In the many studies that have been done studying the effect of vitamin D in different cancer types, there is no straight link between use and benefit," says the study's lead investigator, Leena Hilakivi-Clarke, Ph.D., a professor in the Department of Oncology.

For example, in the colon, vitamin D seems to reduce the risk of cancer development, but it may not have any effect on later stage colon cancer. There is also concern that vitamin D may increase the risk of prostate, esophagus and pancreatic cancer. In work she has conducted in endometrial cancer, Hilakivi-Clarke found that although vitamin D was not beneficial in lean mice, in obese animals it reverses both early and advanced stages of the cancer.

"This is not a vitamin that should be taken lightly," she cautions. "People need sufficient amounts because it has beneficial effects for overall health that have nothing to do with preventing cancer. But for those who want to boost their use of vitamin D, it is important that they have their individual levels tested by a physician, and that they discuss their desire to use supplements."

In their ER- breast cancer study, the researchers fed lean mice two doses of vitamin D - 15 or 20 K international units [IU] VD3 - from puberty onset onwards for 24 weeks. They found that the lower dose (15 K IU) of VD3 significantly reduced mammary tumor incidence as well as time for tumors to develop in lean mice, when compared to mice that were fed control diet. A higher dose (25K IU) was used in mice fed the obesity-inducing diet because vitamin D becomes trapped in fatty tissue and thus is reduced in the blood stream, Hilakivi-Clarke says. Obese mice destined to develop ER- cancer that were given vitamin D developed the highest incidence of breast cancer.

In both mouse models of breast cancer, obese mice developed insulin resistance, and vitamin D supplementation reversed it. However, vitamin D in lean mice tended to reduce insulin sensitivity in both mouse models, she says.

The researchers are currently studying possible mechanisms by which vitamin D may reverse obesity induced increase in breast cancer and insulin resistance, and preliminary results suggest vitamin D reverses the action of genes which promote inflammation, cell proliferation and survival, and this might involve epigenetic modifications.

2 comments:

Jenny: You should always try to get vitamins and minerals naturally--vitamin D from the sun, primarily. I think the evidence overall shows that ER-negative women still benefit from vitamin D, but don't overdo it. Insulin resistance may be a factor in estrogen-negative BC, so if vitamin D reduces it, that is a good thing. This research is on mice. It showed that obese mice were most at risk of TNBC, and obesity has been associated with TNBC in other studies. The message to me, again, is to get natural vitamin D. If you cannot get it from the sun, take a supplement. I can find research that supports 2000 IUs a day.

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When I was diagnosed with hormone-receptor-negative breast cancer, I required a positive attitude of myself—I was not going to let a disease have the upper hand. I hope I can share some at that attitude with you while I offer what I have learned in my trek through this disease as a patient and medical writer.

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Triple-negative breast cancer (TNBC) lacks hormone receptors for estrogen, progesterone, and Her2/neu. It affects about 20 percent of all those with breast cancer. This blog offers information and hope for those with TNBC and other forms of hormone-negative breast cancer.

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